Glaucoma is one of the leading causes of blindness in the world. It affects approximately 66.8 million people worldwide. At least 12,000 Americans are blinded by this disease each year (Kahn and Milton, 1980). Glaucoma is characterized by the degeneration of axons in the optic nerve head, primarily due to elevated intraocular pressure (IOP). One of the most common forms of glaucoma, known as primary open-angle glaucoma (POAG), results from the increased resistance of aqueous humor outflow in the trabecular meshwork (TM), causing IOP elevation and eventual optic nerve damage.
Recent studies have linked POAG and juvenile open-angle glaucoma (JOAG) to the mutation of myocilin (Tamm et al., 2002; Jacobson et al., 2001). Myocilin, a secretory protein was first identified in cultured human TM cells treated with dexamethasome. In situ hybridization experiments revealed that myocilin is present in many ocular tissues including conjunctiva, sclera, TM and cornea and non-ocular tissues such as smooth muscle. In humans, the gene encoding myocilin is located in chromosome 1 (1q21-q31) and was initially named TIGR (TM-Inducible-Glucocorticoid-Response protein) (Jacobson et al., 2001).